Adjustable scaffold



Filed March 18, 1957 4 sheetsrsheet 1 la-l INVENTOR. Mama: J/i JOHNJON BYMQJLQLJW Arum/5K5 y 15, 1958 w. J. s. JOHNSON 2,843,430

ADJUSTABLE SCAFFOLD Filed March 18, 1957 4 Sheets-Sheet 2 INVENTOR. Mama: J, 5, Jam/saw w. J. s. JOHNSON 2,843,430

ADJUSTABLE SCAFFOLD July 15, 1958 V 4 sheetsw-sheet 3 Filed March 18, 1957 &

INVENTOR. Mum $5, Jail/V50 %4.-.Q.,Q;4,M

y 1953 w. J. 5. JOHNSON 2,843,430

ADJUSTABLE SCAFF OLD Filed March 18, 1957 1 4 Sheets-Sheet 4 United States Patent ADJUSTABLE SCAFFOLD Wallace J. S. Johnson, Berkeley, Calif., assignor to Up- Application March 18, 1957, Serial No. 646,665

8 Claims. (Cl. 304-29) This invention relates to scaffolds for use by builders and the like, and particularly pertains to a scaffold having a vertically adjustable platform.

It is the principal object of the invention to provide a scaffold unit which is easily moved from place to place and which has a vertically adjustable platform.

A further object of the invention is to provide a scaffold having generally vertically extending end support member frames with an elevated platform supported by a scissors type structure pivotally mounted on the support member so that as the upper ends of the frames are tilted toward and away from each other, the platform will be raised and lowered, and in which diagonal cross members are pivotally connected to the frame to provide a rigid support for the scissors structure and elevated platform.

A yet further object of the invention is to provide an adjustable scaffold as set forth in the last object which is easily assembled and taken apart to provide for greater adjustability and for ease in storage.

Other objects and advantages will become apparent in the course of the following detailed description.

In the accompanying drawings, forming a part of the specification, and in which like reference numerals are used to designate like parts throughout the same.

Fig. 1 is a front elevational view of the scaffold illustrating the relation of parts when the platform is in its lowermost position.

Fig. 2 is a view similar to Fig. 1 illustrating the relation of parts when the platform is in an elevated position.

Fig. 3 is a side elevational view of the scaffold as shown in Fig. 1 and as viewed from the left of that figure.

Fig. 4 is an elevational view, partly in section, of the scaffold adjusting means.

Fig. 5 is an enlarged elevational detail of a portion of Fig. 1.

Fig. 6 is an enlarged elevational detail of a portion of Fig. 3.

Fig. 7 is a front elevational view, shown partly in section, and taken along the line 7-7 of Fig. 6.

In the drawings, wherein for purposes of illustration is shown a preferred embodiment of the invention, reference numeral 10 indicates generally the scaffold unit,

which is principally constructed of tubular Duralumin or the like, so as to combine high strength with light material, although it is obvious that other materials may be employed, if desired.

The scaffold unit 10 comprises a pair of generally upright rigid rectangular support member frames 11 and 11a connected together by diagonal cross members 13, 14, 16 and 17 extending therebetween. Frame 11, as best seen in Fig. 3, comprises a generally rectangular frame having a pair of upright tubular members 18 and 19 with horizontally disposed rungs 21, 22, 23, 24 and 25, rigidly connected therebetween and thereto, as by welding. The number and the vertical spacing of these rungs are a matter of choice, subject to the limitations to be discussed hereinafter.

Each upright member 18 and 19 carries on its lower end a caster wheel, or roller foot, 26, preferably of the type disclosed in more detail in my United States Patent No. 2,512,941. For the purposes of the present disclosure, it is sufiicient to say that the caster wheel 26 is locked against rolling movement by friction brake 27, when the actuating lever 28 is in the position as shown in Fig. 1. When the lever 28 is pivoted upwardly from this position, the friction brake 27 will be released so that the wheel is free to roll, in order that the scaffold unit may be easily moved from place to place.

Each caster wheel 26 is vertically adjustable with respect to its upright member 18 or 19 by an adjustable supporting leg 29 and locking collar 36, of the type disclosed in greater detail in my United States Patent No. 2,618,496.

The diagonal cross members 13 and 14 are each pivotally connected at one end to rung 23 of frame 11 and at their other end to rung 25a of frame 11a. Similarly, the diagonal cross members 16 and 17 are each pivotally connected at one end to rung 23a of frame 11a and at their other end to rung 25 of Frame 11. As shown in Fig. 7, the pivotal connections herein described are made by means of the special locking hooks 32,. shown in more detail in my United States Patent No 2,665,950. Such hooks have a curved portion 33 adapted to encircle the tubular member to which it is applied, such as rung 23, with the hook 322 being locked into place by spring biased pin 34. With the hook 32 as applied and. locked to rung 23, as shown in Fig. 7, the cross member 13 is free to pivotally rotate around the rung, While separation therebetween is prevented by pin 34. If it is desired to separate the hook 32 from the rung 23, the pin 34 is merely pressed inwardly into the hook 32, and the curved portion 33 is lifted off the rung 23. By the use of such an easily detachable pivotal connection, the entire scaffold may be quickly dismantled, or the different elements may be easily connected together in different arrangements to suit different conditions.

The rungs 23 and 23a are each the same height, or distance, from the bottom ends of the upright members 18, 19 and 18a, 19a, respectively, and the rungs 25 and 25a are spaced equal distances below rungs 23 and 2311, respectively, so that when the scaffold unit 10 is brought to its place of use and leveled by means of the adjustable legs 29, rungs 23 and 23:: will lie in a horizontal plane, and rungs 25 and 25a will lie in a lower horizontal plane.

A scissors structure, generally indicated at 35, comprises a first rectangular frame 36 having a pair of generally diagonally disposed channel beam support members 37 and 38, connected at their lower ends by a cross tube 39 rigidly connected thereto, as by Welding, and connected at their upper ends by a tubular pipe member 41 also rigidly connected thereto, as by welding, and a second rectangular frame 42 having a pair of generally diagonally disposed channel beam support members 43 and 44 connected at their lower ends by a cross tube 46 rigidly connected thereto, as by welding, and connected at their upper ends of a cross tube 47 rigidly connected thereto, as by welding.

The frames 36 and 42 are connected together in a scissors fashion, as shown in Figs. 2 and 3, with a bolt 48 pivotally connecting the adjacent frame members 37 and 43 together centrally intermediate. their ends, and with bolt 49 pivotally connecting the adjacent frame members 38 and 44 together centrally intermediate their ends, whereby thefrarnes 36 and 42 may open and close with respect to each other about an axis extending through bolts 48 and 49. a

Each of the diagonally disposed support members 37, 38, 43 and 44 is provided with one of the locking hooks 32-" previously described whereby the scissors frame 36 may be quickly connected to or disconnected from rung 21 of the support frame 11, and the scissors frame 42 may be quickly connected to or disconnected from the rung 21aof the' support'frame 11a.

An adjusting means 135 is connected between the lower cross tubes 39 and 46 of the scissors frames 36 and 42, respectively, so that a scissors action may be imparted to the scissors structure 35. As best seen in Figs. 3 and 4, a sleeve 136 is loosely mounted on cross tube 39, so as to rotate thereon, and a short cylindrical member 137 is welded thereto with its axis extending radially from the 'sleeve' 136. A cylindrical hub 138 is mounted in the cylindrical member 137 to support one end' of'a righthand threaded member 139, the latter being prevented from-rotating with respect to hub 138 by means of a pin 141. A tubular guide sleeve 142 surrounds the threaded member 139 and is fixed to cylindrical member 137 by -bolt'--143, the bolt also serving to prevent rotation of hub 138.

l A tubular adjusting member 144 is slidably received in 'guide sleeve 142 and'has a right-hand threaded nut 146, "gfixed by screws 147 thereto, in threaded engagement with 'th readed member 139. The other end of the adjusting means 135 is identical to that described above except that the threaded member 139 is provided with left-hand threads and the threaded nut (not shown) on the other end of'adjusting member 144 is provided with mating left-hand threads. A toothed wheel 148, mounted on adjusting member 144 and rotatable by chain 149, enables the adjustting member to rotate so as to thread the nuts 146 on the threaded members 139 and 139a, the left and right-hand threads enabling the adjusting member 144 to "move inwardly into sleeves 142 and 142a simultaneously,

'or to move outwardly from sleeves 142 and 142a simul- "taneously, so that the overall length of the adjusting means 135 may be varied as desired.

'A platform 55 is provided, having a generally reci tangular frame comprised of transverse tubular members "56 and 57 and longitudinally extending tubular members '58 and 59 rigidly connected to each other at their ends. "Transverse member 56 is pivotally received within locking hooks 32 fixed to the upper ends of support members Each end of the platform 55 is provided with a gen- 'erally'rectangular railing section having vertical members 63 and 64 receivable within sockets 66 and 67 fixed to "the platform frame and horizontal railing members 68 and 69 extending between the vertical members and fixed "theretof Longitudinal railing members 71 and 72" are "locked into pla ce 'onto the upper rail members 68 and68a to form a railing completely around the platform 55.

The tubular member 47 extending between support members 43 and 44 is provided to support the ladder 75.

' The ladder preferably comprises channel-shaped side members 76 and 77 with hollow pipe rungs 78 extending therebetween, and a cable 79 is passed through the upper rung 78 to attach onto tubular member 47 by means of hook members 32. Bracket 181, rotatably mounted on rung 22 of frame 11, guides the ladder 75 by means of I the lip 82 overlying the flange of the channel member 77. Similarly, channel member 76 is guided by bracket 83.

In operation, the scaffold unit is wheeled to the point of use, and leveled by means of the adjustment legs 29, so that the platform 55 is level. then raised or lowered, as desired, by pulling on the "chain 149 to rotate the adjusting member '144 in the desired direction to shorten or lengthen the distance be- The platform is tween the lower ends 'of the scissors frames 36 and .42

'4 I and thus to tilt the frames 11 and llainwardly or outwardly from each other. This motion will produce a scissors acton on the upper support members 37, 38, 43 and 44, causing their upper ends to raise or lower. The platform 55 will consequently be raised or lowered, with the longtiudinal members 58 and 59 thereof sliding on the pipe 41 carried by support members 37 and 38. The diagonal cross members 13, 14 and 16, 17 will rotate on the frame rungs to which they are hooked, and each pair of adjacent cross members, such as 13 and 16, will cross each other at the mid-point of the base f ormed by the frame members 11 and 11a, as shown in Figs. 1 and 2. This symmetry will insure that each frame member 11 and' 11a will be tilted to the'same degree, and thus the upper ends of the frames 11 and 11a will lie in a horizontal plane. Consequently, the platform 55 will always be in a horizontal plane as the scissors support members 37, 38, 43 and 44 are all equal in length.

As the'platform55'is raised in height, the lower ends of frames 11-and lla willmove apart and will provide a longer base with resultant gain in stability of the scaffold.

When the platform 55 is at a desired height, the safety chain 85,which is passed around the upper rungs 21 and 21a, is unhooked-from itself, pulled tautly and rehooked to itself so that the upper ends of the frames 11 and 11a will 'beprevented from pulling apart in case'anything would fail in the adjusting means 135, or in case anyone should accidentally manipulate the pull chain 149 so as to ordinarily causethe platform 155 to lower.

The scaffold is capable of further adjustability as to its height because ofits mode of construction. As illustrated, the scissors frames 36 and 42 are attached to the rungs 21 and 21a of support frames 11 and 11a, respectively, to obtain the greatest height of the platform 55 above the ground. 1 If it is desired to have the platform adjustable upwardly from a lower height from the ground, the scissors frames 36 and'42'may be quickly,

and easily disconnected as a unit from the upper rungs 21 and 21a and connected to the rungs 22 and 22a. Or, if desired, the scissors frames may be connected to' rungs 23 and'23a. In the event of any such re-connection, the operation whereby the platform 55 may be vertically adju'sted will remain the same; that is, the adjustment of the adjusting means 135 will cause the scissors structure 35 to raise or lower the platform 155, while causing the supportfram'es 11 and lla'to tilt inwardly or outwardly as the length of the adjusting means is varied.

"The entire 'scaffold unit is quickly disassembled, in case it Is necessary to store 'or transport the scaffold.

' The platform unit 55 is easily removed from the scissors structure 35, by simply disconnecting the locking hooks "32 on theup'per end of the scissors frame 42. The platform railing may then be removed and the platform and its railing'niay be stored flat.

The entire scissors structure 35 may be quickly removed'from' the support members 11 and 1111 by merely releasing the locking hooks 32 on the lower ends of the scissors frames 36 and 4 2. The adjusting means 135 is then lengthened so that the scissors structure becomes flat.

Similarlyhthe support frames 11 and 11a maybe quickly dismantled by disconnecting the diagonal :cross members 13, 14, 16'and 17,"so that these units may then be stored flat.

It is to be understood that the form ofthe invention,

herewith shown and described, is to betaken as a preferred embodiment of the same,-and that various-changes 1n the' shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention, or the scope of the attached claims.

Having thus describedm-my innvention, what 'I claim and desire to secure by Letters Patent is:

1. An'adjustabl'scaifold. comprising: a-first upwardly"ext'ending rigid 'support'member; a second upwardly j i extending rigid support member; a first rigid cross member; a first pivotal connection between one end of said first cross member and said first support member; a second pivotal connection between the other end of the said first cross member and said second support member; a second rigid cross member; a third pivotal connection between one end of said second cross member and said second support member; a fourth pivotal connection between the other end of said second cross member and said first support member, said first and third pivotal connections being the same height from the lower ends of said first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid support member pivotally connected at one end thereof to the upper end of said first support member; a fourth rigid support member pivotally connected at one end thereof to the upper end of said second support member, said third and fourth support members being pivotally connected to each other intermediate their one ends; a rigid platform member pivotally connected at one end thereof to the other end of said third support member and slidably resting intermediate its ends on the other end of said fourth support member; and means for moving said one ends of said third and fourth support members towards and away from each other.

2. An adjustable scaffold comprising: a first upwardly extending rigid rectangular frame; a second upwardly extending rigid rectangular frame; a first rigid cross member; a first detachable pivotal connection between one end of said first cross member and said first frame; a second detachable pivotal connection between the other end of said first cross member and said second frame; a second rigid cross member; a third detachable pivotal connection between one end of said second cross member and said second frame; a fourth detachable pivotal connection between the other end of said second cross member and said first frame, said first and third pivotal connections being the same height from the lower ends of said first and second frames and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a first rigid support member detachably pivotally connected at one end thereof to the upper end of said first frame; a second rigid support member detachably pivotally connected at one end thereof to the upper end of said second frame, said first and second support members being pivotally connected to each other intermediate their one ends; a rigid rectangular platform member detachably pivotally connected at one end thereof to the other end of said first support member and slidably resting intermediate its ends on the other end of said second support member; and means for moving said one ends of said first and second support members towards and away from each other.

3. An adjustable scaffold comprising: a first upwardly extending rigid rectangular support member; a plurality of spaced apart roller feet on the lower end of said first support member; a second upwardly extending rigid rectangular support member; a plurality of spaced apart roller feet on the lower end of said second support member; means to adjust the spacing of said roller feet from the lower ends of said first and second support members; a first rigid cross member; a first pivotal connection between one end of said first cross member and said first support member; a second pivotal connection between the other end of said first cross member and said second support member; a second rigid cross member; a third pivotal connection between one end of said second cross member and said second support member; a fourth pivotal connection between the other end of said second cross member and said first support member, said first and third pivotal connections being the same height from the lower ends of said first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid support member pivotally connected at one end thereof to the upper end of sa d first support member; a fourth rigid support member pivotally connected at one end thereof to the upper end of said second support member, said third and fourth support members being pivotally connected to each other equidistant from their one ends; a rigid platform member pivotally connected at one end thereof to the other end of said third support member and slidably resting intermediate its ends on the other end of said fourth support member; and means for moving said one ends of said third and fourth support members towards and away from each other.

4. An adjustable scaffold comprising: a first upwardly extending rigid rectangular support member; a second upwardly extending rigid rectangular support member; a first rigid cross member; a first pivotal connection between one end of said first cross member and said first support member; a second pivotal connection between the other end of said first cross member and said second support member; a second rigid cross member; a third pivotal connection between one end of said second cross member and said second support member; a fourth pivotal connection between the other end of said second cross member and said first support member, said first and third pivotal connections being the same height from the lower ends of said first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid support member pivotally connected at one end thereof to the upper end of said first support member; a fourth rigid support member pivotally connected at one end thereof to the upper end of said second support member, said third and fourth support members being pivotally connected to each other at their midpoints; a rigid rectangular platform member pivotally connected at one end thereof to the other end of said third support member and slidably resting intermediate its ends on the other end of said fourth support member; a rigid adjustment member pivotally connected at one end thereof to said one end of said first support member and pivotally connected at the other end thereof to said one end of said second support member; and means to vary the length of said adjustment member 5. In a device as set forth in claim 4, further including a safety chain connected between the upper ends of said first and second support members and. adjustable in length to limit the movement of said ends away from each other.

6. An adjustable platform comprising: a first upwardly extending rigid rectangular support member having a plurality of horizontal rungs; a second upwardly extending rigid rectangular support member having a plurality of horizontal rungs; a first rigid cross member; a first pivotal connection between one end of said first cross member and said first support member; a second pivotal connection between the other end of said first cross member and said second support member; a second rigid cross member; a third pivotal connection between one end of said second cross member and said second support member; a fourth pivotal connection between the other end of said second cross member and said first support member, said first and third pivotal connections being the same height from the lower ends of said first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid support member; means to detachably and pivotally connect one end of said third support member to a selected rung of said first support member; a fourth rigid rectangular support member; means to detachably and pivotally connect one end of said fourth support member to a selected rung of said second support member; said third and fourth support members being pivotally connected to each other intermediate their ends; and means for moving said one ends of said third and fourth support members towards and away from each other.

7, An adjustable platform comprising: a first upwardly extendingrigid rectangular support member having a plurality of horizontal rungs; a second upwardly extending rigid rectangular support member having a plurality of horizontal rungs; a first rigid cross member; a first detachable pivotal connection between one end of said first cross member and one of said rungs of said first support member; a second detachable pivotal connection between the other end of said first cross member and one of said rungs of said second support member; a second rigid cross member; a third detachable pivotal connection between one end of said second cross member and one of said rungs of said second support member; a fourth detachable pivotal connection between the other end of said second cross member and one of said rungs of said first support member, said first and third pivotal connections being the same height from the lower ends of said first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid rectangular support member; means to detachably pivotally connect said third member at one end thereof to a selected rung of said first support member; a fourth rigid rectangular support member; means to detachably and pivotally connect said fourth member at one end thereof to a selected rung of said second support member; said third and fourth support members being pivotally connected to each other equidistant from their one ends; a rigid rectangular platform member pivotally connected at one end thereof to the other end of said third support member and slidably resting intermediate its ends on the other end of said fourth support member; and means for moving said one ends of said third and fourth support members towards an'd away from eachrother.

8; An adjustable scaffold comprising: a first upwardly extending; rigid support member; a second upwardly extending rigid'support member; afirst rigid cross member; a first pivotal connection between one end of said first cross member and said first support member; a second pivotal connection between the other end of said first cross' member and said second support member; asecond rigid cross member; a third pivotal connection between one end of said second cross member and said second support member; a fourth pivotal connection betweenthe other end of said second cross member and said first support member, said first and third pivotal connections being'the same height from the lower ends of said-first and second support members and said second and fourth pivotal connections each being an equal distance below said first and third pivotal connections; a third rigid support member pivotally connected at one end thereof-to the upper end of said first support member; a fourth rigid support member pivotally connected at one end References Cited in the file of this patent UNITED STATES PATENTS 399,220 Tirnroth Mar. 5, 1889 1,597,265 Cashiere Aug. 24, 1926 1,636,085 'WitteX July 19, 1927 

